A frequent problem in producing thermoplastic molded articles of complex geometry is the unevenness of flow of the molded plastic into the mold resulting in poor quality in the finished product and difficulty in releasing the product from the mold. This is particularly so in the molding of partitioned container-like devices, such as battery casings, where the uneven flow of thermoplastic material into the mold cavity can, for example, cause unequal pressure distribution on opposite sides of the core elements in the mold defining the partitions. This, in turn, causes shifting of the cores and, ultimately, varying wall thicknesses in the molded product.
Another problem is the complexity and expense of manufacture of the mold structure used for making such containers. Also, removal of the molded part from the mold cavity is a further problem.